Postoperative Analgesia in Children- Comparative Study between Caudal Bupivacaine and Bupivacaine plus Tramadol

Summary Thirty children, ASA I-II, aged between 2yrs-5yrs, undergoing sub umbilical operation (inguinal and penile surgery) were selected for this double blind study. They were randomly divided in two groups, group Aand group B. Group A (n=15) received 0.25%bupivacaine 0.5ml.kg -1 and Group B(n=15) received0.25% bupivacaine 0.5 ml.kg -1 and tramadol 2mg.kg -1 as single shot caudal block. Postoperative pain was assessed by a modified TPPPS (Toddler-Preschool Postoperative Pain Scale) and analgesic given only when the score was more than 3. In the first 24 hrs it was observed that the mean duration of time interval between the caudal block and first dose of analgesic was significantly long(9.1hrs) in Group B as compared to Group A (6.3hrs) which was much shorter(p<0.01).There was no significant haemodynamic changes, motor weakness or respiratory depression in both groups. This study concluded that addition of tramadol 2mg.kg -1 to caudal 0.25% bupivacaine 0.5ml.kg -1 significantly prolong theduration of postoperativeanalgesia in children without producing much adverse effects.


Introduction
The society of Paediatric Anaesthesia 1 , on it's15 th annual meeting at New Orleans, Louisiana (2001) clearly defined the alleviation of pain as a"basic human right",irrespective ofage, medicalcondition, treatment, primary service response for the patient care or medical institution. Finely et al 2 observed that many types of so called "minor" surgery (e.g. circumcision) can cause significant painin children.
The goalof post operative pain relief is to reduce or eliminate pain with minimum side-effects and in our setup as cheaply as possible.Effective painrelief means a smooth postoperative period, increased patient compliance and an early discharge from hospital. Langlade et al 3 suggested that the postoperative pain treatment must be included in the anaesthetic planning even beforeinduction of anaesthesia, adoptingthe ideaof 'managing pain before it occurs'.
Over the years various regionalanaesthetic procedures has gained popularity for postoperative analgesia because in addition to providingeffective postoperative pain relief, they also reduce the requirement of general anaesthesiaintraoperatively without significant side-effects and maintaining a smooth intra and postoperative period. Caudal block has proved useful in a variety of subumbilical operations 4 in children for providing both intra operative and post operative analgesia. Objective of present study was to compare the quality and duration of analgesia , after a single shot caudal blockwith bupivacaine alone and bupivacaine plus tramadol, and thereby try to find out whether tramadol can be an effective adjuvant to bupivacaine for providingpostoperative analgesia in children undergoing subumbilical surgeries.

Methods
After obtaininginstitutional approvaland paren-tal written informed consent, thirty children aged between 2-5yrs , weighing between 10-18 Kg and of ASA I and II physiologic status were enrolled for the study.These patientswere scheduled for sub-umbilical surgeries like herniotomy and penile surgery under general anaesthesia by a single surgeon. The patients were randomly allocated in two groups.
The patients were induced with halothane and 50% nitrous oxide in oxygen inhalation via face mask. Intravenous cannulation was done using22G cannula, then atropine 0.02mg.kg -1 , ondansetron 0.1mg.kg -1 and midazolam 0.1mg.kg -1 were given i.v as premedication.After induction, caudal block was then given in right lateralposition by a 22G needle underaseptic condition. Syringes containing an equal volume of either 0.25% bupivacaine 0.5ml.kg -1 or 0.25% bupivacaine 0.5ml.kg -1 plus tramadol 2mg.kg -1 wereprepared and given to theinvestigator who wasblinded to theidentity of drug(s).He gave the caudal blocks. Then the surgery was continued under inhalationalanaesthesia via mask. Intraoperative heart rate, respiratory rate, blood pressure (NIBP) and oxygen saturation (SpO2) was monitored.After recoveryfrom generalanaesthesia the patient was shifted to PACU and his vitals and pain was assessed by a 10-point TPPS score 5 (Table 1) by a blinded investigator .The child's motor power, any side-effects and sedation score(0= Eyes open, 1= Eyes open to speech, 2=Eyes open when shaken, 3= unrousable) was also noted. Assessment was done every 5-min for the first 30-min, then every 15-min for next 1hr, then hrly for next 2 hrs and then at 4, 6, 8, 10, 14, 18 and 24hr by the same blinded investigator.

Data Processing
ANOVAwith multiple comparisons was used for comparisons between the groups. UsingChi squared (X 2 ) test compared the non-parametric data. p<0.05 was regarded as statistically significant.

Results
The two groups were comparable in age, weight and duration of surgery(Table2).
Whilecomparing the quality of postoperative analgesia between the two groups it was seen that the  Group A started having mild pain after 3hrs and the pain was significant after 6hrs whereas in Group B the child was pain free for almost 5hrs and started having significant pain after 8 hrs which needed analgesic supplementation with syrup Paracetamolat thedose of 10 mg.kg -1 . Significant pain is described as one that has a pain score of more than 3 (Table 3).
When pain score was plotted against time in a graph, it was seen that the score was 0 upto 2 hrs and then started to increase and reached a score of 3 only after 9 hrs in Group B ,where as in Group A the pain score started to attain 3 after 6 hrs. (Fig 1). and 13.3% in Group B. Nausea and vomiting was slightly more in Group B(26.67%)than GroupA(20%), (Table 5).

Fig 1 Changes in pain score along with time
It was also seen that the children in Group A needed more doses of paracetamol syrup in first 24 hrs than Group B ( Table 4).
Thevitals of patients in both groups remain stable during operation and the incidences of emergence agitation were much less in both groups rather than the patients undergoingsurgery under general anaesthesia without caudal block.
There was no major difference in sedation score between the two groups after recovery. 13.3% patients in Group A and 6.6% in Group B developed motor weakness. It was also observed that incidences of postoperative urinary retention was 20% in Group A

Discussion
Ease of performance and reliability makes caudal blockthemost commonlyperformed blockin children. Caudaladministration of bupivacaine is a widespread regionalanaesthetic technique for intra-and postoperative analgesia during lower limb, anoperineal, penoscrotaland abdominalsurgical proceduresin children [6][7][8] . Tramadolis a centrally actingopioid analgesic, used for treatingmoderate to severe pain. It is a synthetic agent, made of racemic mixture of two enantiomers-(+) tramadol and (-) tramadol and it appears to have actions at the  -opioid receptor as wellas the noradrenergic andserotonergic systems 9 .Tramadolwas developed by the German pharmaceutical company GrünenthalGmbH in the late 1970s and marketed under the trade name Tramal.As an analgesic it's equipotent to meperidine without any respiratory depressant action. The most commonly reported adverse drug reactions are nausea, vomiting, sweatingand constipation. Drowsiness is reported, although it is less of an issue than for opioids.
In our study, we found that by adding tramadol 2mg.kg -1 to caudal bupivacaine (0.025%) 0.5ml.kg -1 in childrenundergoingsub-umbilicaloperation, significantly increased the duration of pain free period postoperatively. Similar results were reported by Gune et al 10 duringa studyof childrenundergoinghypospadias repair showedthat caudaltramadolprovides better and longerlastingpostoperativeanalgesia thani.v. tramadol. Senelet al 11 in a study on children undergoing hernior-rhaphy showed that, caudal administration of bupivacaine with the addition of tramadol resulted in superior analgesiawith alonger periodwithout demand for additional analgesics compared with caudal bupivacaine and tramadol alone without an increase of side effects. The incidence of emergence agitation, which is frequently seen during recovery from inhalationalanaesthesia in children, were much less in children with preoperative caudal blockin bothgroups and it was more less in Group B and this is supported by a previous study of Weldon et al 12 who reported that effective postoperative analgesia may reduce the incidence of emergence agitation with sevoflurane anaesthesia. The degree of sedation was comparable in two groups. The potency of single shot caudal bupivacaine was increased by addition of tramadol because in our set up it wasneither technically possible nor cost effective to use caudal epiduralcatheter and maintain postoperative analgesia with bupivacaine alone.A prolong and effective postoperativeanalgesia tochildren means a coo perative child with less emotional and haemodynamic stress and rapid recovery withless hospital stay.Mean durationof postoperativeanalgesia with caudal bupivacaine was 6.3hrs whereas with addition of tramadolit increased up to 9.1 hrs, without increasing the dose as wellas the side effects of bupivacaine as it was shown in various studies 13,14 .A higher dose of tramadol could have caused nausea and vomiting whereas increasingthe dose of bupivacaine could have caused more motor weakness and urinary retention. 15 Our study concluded that caudal administration of tramadol 2mg.kg -1 along with 0.25% bupivacaine 0.5ml.kg -1 significantly increasedthe durationand quality of postoperative analgesia in children undergoing subumbilical operation, without producingsignificant adverse effects.